Question 10 of 20: Long-Term Landfill Closure Plan

Question 10: Long-Term Landfill Closure Plan (3 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

A long-term closure plan must address: (1) final cover system design — low-permeability barrier layer, drainage layer and vegetative/protective cover layer, graded to shed precipitation and minimize infiltration while resisting erosion; (2) post-closure leachate management — continued leachate collection, treatment and monitoring for the regulatory post-closure period (commonly 25–30 years, until leachate strength stabilizes to acceptable levels); (3) landfill gas management — continued gas collection/flaring or beneficial use as production continues to decay after closure (see Questions 13–14); (4) groundwater and surface-water monitoring network, maintained through the post-closure period to detect any liner/cover failure early; (5) settlement monitoring and cover maintenance, since differential settlement can crack the cover and create ponding or preferential infiltration pathways requiring periodic repair; (6) long-term financial assurance — a dedicated closure/post-closure trust fund sized to cover the full monitoring and maintenance period, since the responsible party's tenure may end before the site's environmental obligations do; and (7) end land-use planning, since post-closure settlement and gas generation constrain what the site can safely be redeveloped for.

Provincial landfill closure regulations typically require the closure plan and its financial assurance to be approved and in place well before the site actually stops accepting waste, precisely because the post-closure obligations (items 2–6 above) are decades-long and must not depend on the continued financial health of the original operator. A closure plan is therefore best understood as an operating-phase design deliverable, not an afterthought prepared once the very last load of waste has already been placed. Practically, this means contributions to the closure/post-closure trust fund should accrue on a per-tonne-disposed basis throughout the site's active life, so the full fund is already in place on closure day rather than requiring an unaffordable lump-sum payment precisely when the site has stopped generating any tipping-fee revenue to help cover it.